Atomistic and Microstructural Computational Fatigue Design and Integrated Creep-Fatigue Theory for High-Temperature Alloys

高温合金的原子和微观结构计算疲劳设计和集成蠕变疲劳理论

• 批准号: RGPIN-2019-06264
• 负责人: Liu, Rong
• 金额: $ 2.33万
• 依托单位: Carleton University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=715797
• 关键词: Atomistic; Microstructural; Computational; Fatigue; Design

Fatigue accounts for at least 90 percent of all service failures of components subjected to cyclic loading, as experienced by automobiles, aircraft, compressors, pumps, turbines, etc. Traditionally, engineers and researchers have to perform testing to determine a material's fatigue property, which results in high costs in time and money, thus prolonging the development cycle in material and component design for mechanical/structural systems. Recent research has reported that the low cycle fatigue (LCF) life of a material can be formulated in terms of material's physical properties including Burgers vector, shear modulus and surface energy. High cycle fatigue (HCF) is, in essence, a process of microstructural LCF crack nucleation plus crack propagation. Enlightened by these understandings, a computational fatigue design approach is proposed in the present research, aiming to search for new high-temperature alloys with superior fatigue resistance. A microstructure-based numerical model combined with first-principles density functional theory (DFT) will be developed and then used to predict the crack nucleation life of polycrystalline metals for a wide spectrum of loading from LCF to HCF. Furthermore, utilizing the deformation mechanisms involving glide and climb of dislocations within grain interior and along grain boundaries, a holistic theoretical framework the integrated creep-fatigue theory (ICFT) for high-temperature alloys will also be proposed in the present research. The theoretical model established based on the first cornerstone leads to constitutive laws encompassing all possible deformation mechanisms and that based on the second cornerstone describes the damage accumulation process leading to fracture, and thus defines the life under general loading conditions that involve a combination of fatigue, creep and thermomechanical fatigue. Using this theory, only limited laboratory-testing will be required for a new material development such that material behavior under complicated loading conditions can be linked to the fundamental deformation mechanisms. Once established, the proposed theory and model will speed up material development and application to meet the fast-growing technological demands and stringent environmental requirements in the 21st century and future. They also have a great implication in prognosis and health management of existing or newly designed mechanical systems, with accurate life prediction, offering tremendous savings in life cycle management. In addition to the benefits for the research field, the proposed research has also planned the training of Highly Qualified Personnel (HQP) with serious consideration of Equity, Diversity and Inclusion (EDI). The time and cost saving using this research outcomes to design new materials and maintain mechanical systems to meet continuously increasing requirements for the gas turbine industry will certainly benefit and contribute to the economy and society of Canada.

在汽车、飞机、压缩机、泵、涡轮机等承受循环载荷的部件的所有使用故障中，疲劳至少占 90%。传统上，工程师和研究人员必须进行测试以确定材料的疲劳特性，这导致时间和金钱成本高昂，从而延长了机械/结构系统材料和组件设计的开发周期。最近的研究表明，材料的低周疲劳 (LCF) 寿命可以根据材料的物理特性（包括伯格斯矢量、剪切模量和表面能）来计算。高周疲劳（HCF）本质上是微观结构LCF裂纹形核加裂纹扩展的过程。受这些理解的启发，本研究提出了一种计算疲劳设计方法，旨在寻找具有优异抗疲劳性能的新型高温合金。将开发基于微观结构的数值模型与第一原理密度泛函理论 (DFT) 相结合，然后用于预测从 LCF 到 HCF 的宽范围载荷下多晶金属的裂纹成核寿命。此外，利用涉及晶粒内部和沿晶界的位错滑移和攀爬的变形机制，本研究还将提出高温合金的综合蠕变疲劳理论（ICFT）的整体理论框架。基于第一个基石建立的理论模型导致涵盖所​​有可能的变形机制的本构定律，而基于第二个基石的理论模型描述了导致断裂的损伤累积过程，从而定义了涉及疲劳、蠕变和热机械疲劳。利用这一理论，新材料的开发只需要有限的实验室测试，这样复杂负载条件下的材料行为就可以与基本变形机制联系起来。一旦建立，所提出的理论和模型将加速材料的开发和应用，以满足21世纪和未来快速增长的技术需求和严格的环境要求。它们还对现有或新设计的机械系统的预测和健康管理具有重大影响，具有准确的寿命预测，可在生命周期管理中节省大量成本。除了对研究领域的好处外，拟议的研究还规划了高素质人才（HQP）的培训，并认真考虑了公平、多样性和包容性（EDI）。利用这项研究成果来设计新材料和维护机械系统，以满足燃气轮机行业不断增长的要求，节省时间和成本，这肯定会给加拿大的经济和社会带来好处和贡献。